Print on demand (POD) is a printing technology wherein digital or hard copies of a document such as a book or magazine are printed in small quantities or even one at a time, typically when an order for the document has been received. POD is useful, for example, for specialty documents, test marketing documents, and when producing copies of older works that are out of print. Digital printing technologies facilitate the POD process, since it generally is not economical to print single copies with prior printing technologies such as letterpress and offset printing.